The present invention relates to a device for regulating the idling speed of rotation of an Otto engine, particularly in an automotive vehicle in general.
In particular the invention relates to a device for regulating the idling speed of rotation of an Otto engine, particularly in an automotive vehicle, which has, within an intake pipe, a throttle valve which is under the action of at least one return spring and can be displaced by a gas pedal, having a rotary element attached firmly to the throttle valve and on which at least one rotary stop limiting an angular range of the idling admission regulation is formed and which can be coupled with the actuator which is provided for actuating a closure member which determines the idling air throughput.
In one such known device for regulating the idling speed of rotation, the devide is combined with a device for controlling the speed of travel of the automotive vehicle in such a manner that a single common actuator for control of the speed of the vehicle and regulation of the idling speed of rotation is sufficient (European Patent Application Publication No. 0 050 707). Within a first operating range, a closure element for regulating the idling speed of rotation can be actuated by the actuator; and, within a second operating range, a setting element for the control of the speed of the vehicle can be actuated by the actuator. The closure element for regulating the idling speed of rotation can be actuated by the actuator and, in its turn, the setting element for the control of the speed of the vehicle can be actuated by the closure element. If the closure element for the regulating of the speed of rotation is brought into operational connection with the setting element of the vehicle speed control only in the open end position of said closure element, this makes it possible that, in the idle position of a set-point setting means or of a gas pedal, only the closure element for the regulating of the idling speed of rotation is actuated. On the other hand, if the set-point setting means is moved out of its position of rest then the actuator, via the closure element for the regulating of the idling speed of rotation, displaces the setting element for the control of the speed of the vehicle. The setting element for the control of the speed of the vehicle is normally a throttle valve which is located in fixed position on a hollow shaft and is urged by a spring into an end position; the end position limits the rotary movement and corresponds to the closed position of the throttle valve. Within the hollow shaft there is mounted an actuation shaft on which the actuator acts. Between the actuation shaft and the hollow shaft there is positioned a clutch by which the rotary movement of the actuation shaft is transmitted to the hollow shaft after a rotation of the actuation shaft out of a position, corresponding to the closed position of the closing element for regulating idling speed, into a position corresponding to the opened position of the closure element. For this purpose, a radially directed stop which engages into a groove in the hollow shaft and/or the actuation shaft can be provided as coupling on the actuation shaft and/or on the hollow shaft. As closure element for the regulating of the idling speed of rotation, an idling valve is connected to the actuation shaft. A coaxial opening in the throttle valve can be opened to a greater or lesser extent by means of the idling valve. Air can accordingly flow from the region of the intake pipe in front of the throttle valve into the region behind the throttle valve and adjust the idling speed of rotation. The device of the foregoing patent therefore provides for a change in the characteristic between the operating range of the closing element for the regulating of the idling speed of rotation and the operating range of the setting element for the regulating of the speed of the vehicle, both of which are displaced by the same actuator. The actuator is therefore to be designed with sufficient capacity to displace the throttle valve against the return spring as setting element for the control of the vehicle speed.
For the same reason, the control electronics must make available a suitable amount of energy for operating the actuator. Since the same actuator is to regulate the idling speed and effect control of the speed of the vehicle, coordinated control and regulating circuits must be provided, these necessitating corresponding expense of manufacture and adjustment. Such vehicle speed control furthermore normally presupposes an electric set-point setting means for the gas-pedal position. Aside from this, the expense for the manufacture of the throttle valve, which is intended to close the intake pipe at one end position, and for the idle valve which is intended to open or close the coaxial opening in the throttle valve to a greater or lesser extent, is high, particularly because of the sealing problems inherent therein.